Modern motion editing software applications provide a number of tools and user interface elements that enable users to create and manipulate highly complex animation productions. One example of such a user interface element is an animation timeline that provides a graphical representation of the various visual assets comprising an animation production. An animation timeline typically includes a horizontal timeline axis and a number of horizontal bars positioned along the axis. Each of the horizontal bars represents a particular visual asset forming part of the animation production, and also provides a visual indication of the start and end points of the asset with respect to the timeline axis. A user can manipulate the bars to shorten or lengthen corresponding assets. Examples of commercially available motion editing software applications that provide some form of animation timeline interface include Final Cut Pro® (Apple Inc., Cupertino, Calif.), Windows Movie Maker (Microsoft Corporation, Redmond, Wash.) and After Effects® (Adobe Systems Incorporated, San Jose, Calif.).